We suggest using your molcajete (Mexican mortar and pestle) to prepare this rub, rather than a coffee grinder / food processor.

In a small heavy skillet dry-roast oregano over moderate heat, shaking skillet occasionally, until fragrant and beginning to brown, about 2 minutes, and transfer to a small bowl. Cool oregano completely and in an electric coffee/spice grinder grind fine.

In a heavy skillet heat oil over moderately high heat until hot but not smoking and, using tongs, fry chiles, 1 to 2 at a time, turning them, until puffed and just beginning to brown, about 10 seconds. (Do not let chiles burn or rub will be bitter.) Transfer chiles as fried to paper towels to drain and cool until crisp.

Wearing rubber gloves, break chiles into pieces and in coffee/spice grinder grind fine in batches. In a food processor grind oregano and chiles with garlic and salt until mixture is a shaggy, saltlike consistency. If mixture seems moist, on a large baking sheet spread it into a thin, even layer and dry in middle of an oven set at lowest temperature until no longer moist, about 1 hour. Wearing rubber gloves, break up any lumps with your fingers. (Chipotle rub keeps in an airtight container, chilled, 6 months. Regrind rub before using.)

la parilla by chef reed hearon